Thoughts on language-level configuration support?

jfager jfager at gmail.com
Tue Mar 31 15:47:58 CEST 2009


On Mar 31, 5:57 am, Kay Schluehr <kay.schlu... at gmx.net> wrote:
> On 30 Mrz., 15:40, jfager <jfa... at gmail.com> wrote:
>
>
>
> > I've written a short post on including support for configuration down
> > at the language level, including a small preliminary half-functional
> > example of what this might look like in Python, available athttp://jasonfager.com/?p=440.
>
> > The basic idea is that a language could offer syntactic support for
> > declaring configurable points in the program.  The language system
> > would then offer an api to allow the end user to discover a programs
> > configuration service, as well as a general api for providing
> > configuration values.
>
> > The included example implements the first bit and hints at the third,
> > defining a function that looks up what variable its output will be
> > assigned to and tries to find a corresponding value from a
> > configuration source.  It's very preliminary, but I hope it gives a
> > flavor of the general idea.
>
> > Any thoughts or feedback would be greatly appreciated.
>
> The problem with your idea is that those declared declaration points
> can be overlooked no matter how much syntactical support is added.
> Lets say a resource file is loaded and there are a few of the config-
> properties declared in modules you have written. Now an object wants
> to access a resource defined in the file and fails because the
> resource providing property could not be found since the property
> defining module wasn't loaded yet and the property couldn't register
> itself. That's why things are centralized as in optparse and the
> workflow is  designed upfront or things are implemented locally and
> individual units have to take care of their own.

What is a resource file?  How am I accessing the "resource-providing
property" of an unloaded module? That is, if a module isn't loaded,
how do I know about its properties?  Or conversely, if I know about
its properties, why isn't the module loaded?  In other words, why
would accessing a configuration point be any different than accessing
any other name in a module?



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